The present invention relates to a process and system to dehydrate sludge or other residues such as pulpy residues.
There are presently known numerous dehydration devices wherein a residue is passed between two endless belts which press against the residue and thereby extract water from the residue. However, in operating such devices it is necessary to attempt to control the tension of the belts, both to control the thickness of the residue filter cake formed, and to account for tension variations in the material forming the belts. Past attempts to control belt tension have involved mechanical devices, such as adjustable screw settings or springs. However, such devices have the inherent disadvantages of partially stretching the belts when the residue filter cake is not yet formed. Other prior art attempts to control the movement and tension of the belts have involved the use of gear wheel drives. However, such drive systems are inherently expensive and are additionally difficult to protect against corrosion from the residue.